A phase scanning method as a conventional representative method is illustrated in FIG. 1.
In the phase scanning method as a representative electronic scanning method, phase shifters 301 to 304 are respectively connected to a plurality of antenna elements 305 to 308, and a single phase controller 311 is connected to each of the phase shifters 301 to 304. A phase shift amount is controlled by the phase controller 311, and beam scanning is performed.
As the phase shifters 301 to 304, an easily-controlled digital phase shifter is generally used.
In the conventional phase scanning method, a wideband signal generated in an impulse generator 310 is distributed by an electric power distributor 309 to be supplied to each of the antenna elements 305 to 308.
Since a frequency band of a normal radar is narrow, the electric power distributor 309 and the phase shifters 301 to 304 do not vary widely, and thus fabrication is easy.
However, as with a UWB radar, it is difficult to fabricate a phase shifter having an occupied band of not less than 500 MHz and the phase shift amount is flat, and in addition, it is complex to control the phase shifter.
When a UWB radar is constituted by the conventional phase scanning method, a high-priced phase sifter is used, and in addition the number of components is large, and therefore, the cost may be increased.